Figure 81: Toque speed characteristics of series and parallel wired stepper motors The stepper motor used is an 8-wire 2-phase motor, enabling it to be wired in either a bipolar series or bipolar parallel configuration. Because series wired coils have greater inductance they tend to produce more torque at lower speeds, while at higher speeds

Control System Overview The displacer in the prototype engine is driven by means of an electronic stepper motor. Stepper motors allow precise position control as they move one ‘step’ at a time. In the case of the motor used here, a step is 1.8°, and within that step a ‘microstep’ resolution can be defined, down

The second design iteration seeks to optimise parameters from the first iteration within the constraints already established, to arrive at the final working design for the engine. Piston and Con-Rod Design The requirements of the piston are that it: • Is as light as possible • Perfectly seals the gas • Has minimal mechanical friction

Design Overview Because of the low temperature difference given, power and efficiency will be inherently low. In order to reach the target power of 500 W and keep the engine a reasonable size, the engine should be pressurised. Essentially, pressurising the engine puts more moles of working gas into the same space, meaning higher specific

The objective of this project was to design and build a prototype Stirling Engine capable of generating electric power from low grade geothermal heat. Low grade geothermal heat is essentially hot water, i. e. sub 100°C water that cannot be effectively used by traditional geothermal harnessing techniques which require steam. The target power output for

Advantages • High potential efficiency (Carnot limit). In practice the best Stirling engines can have efficiencies of 40% or more. The record for heat input to electrical power output is held by Stirling Energy Systems for one of their solar dish Stirling engines, at 31.25% of solar energy converted to grid-level electricity [40]. • Ability

Broadly speaking, a Stirling Engine will fall under one of the four main categories described here, being either alpha, beta, gamma or free piston configurations. There are Other obscure types of engine such as the thermoacoustic engine and the fluidyne engine which were both discussed briefly in Section 1.4. Alpha (a) Configuration The alpha configuration

Crankshaft The crankshaft is usually a traditional crankshaft such as that found in an internal combustion engine. It is a rotating shaft with an offset crank to which the power piston is attached via a connecting rod or con-rod. The length of the crank determines the stroke of the power piston. All power produced by

“In all places where there exists a difference of temperature, there can be a production of motive power. ” — Sadi Carnot, 1824 Stirling Engine Components A Stirling Engine always has 5 main parts to it that are essential to its operation. Figure 17 below shows one of the Stirling brothers’ early engines where the

STM Corporation STM Corporation, formerly known as Stirling Thermal Motors Inc., was founded by Dr. R. J. Meijer (formerly of Philips) who is the holder of numerous patents on the Stirling engine and inventor of the rhombic drive. They own the rights to a great deal of the Patents from the Philips development era, and